Processing Circuit Switched Services in an Evolved Packet Network

ABSTRACT

The present invention discloses for the ability for processing circuit switched (CS) services in an evolved packet network. For example, embodiments provide a method that includes: by a mobility management entity (MME), receiving a mobile terminated (MT) service indication from a mobile switching center (MSC); sending the MT service indication to user equipment (UE); and receiving an MT service response returned by the UE and performing subsequent operations according to the MT service response. In the method of the present invention, when an MT service arrives, the MME does not trigger the evolved NodeB (eNodeB) to hand over the packet switched (PS) services of the UE but notifies the UE of the MT service and performs subsequent operations according to the MT service response returned by the UE, thus avoiding the waste of network resources caused by a meaningless handover of PS services.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/831,437, filed on Jul. 7, 2010, which is a continuation ofInternational Application No. PCT/CN2008/073200, filed on Nov. 26, 2008.The International Application claims priority to Chinese PatentApplication No. 200810002762.X, filed on Jan. 16, 2008. Theafore-mentioned patent applications are hereby incorporated by referencein their entireties.

FIELD OF THE INVENTION

The present invention relates to communications technologies, and inparticular, to processing circuit switched services in an evolved packetnetwork.

BACKGROUND OF THE INVENTION

To answer the challenge of wireless broadband technologies and maintainthe leadership of the 3^(rd) Generation Partnership Project (3GPP)networks, the 3GPP organization prepared a long term evolution (LTE)plan at the end of 2004. Directed by the LTE plan, new mobilecommunications network architecture is defined, where only the packetswitched (PS) domain remains. The architecture is called an evolvedpacket system (EPS).

To enable circuit switched (CS) services in an EPS network, a prior artprovides a method for processing CS services in an EPS network, whichmay be described as a CS fallback method.

When a mobile switching center (MSC) receives a mobile terminated (MT)service, such as a CS voice call, the MSC sends a page message to amobility management entity (MME) and the MME pages user equipment (UE)via the EPS network. When an evolved NodeB (eNodeB) receives the pagemessage, the eNodeB first executes a PS service handover, that is, theeNodeB hands over the ongoing PS service of the UE to the PS domain of ageneral packet radio service/universal mobile telecommunications system(GPRS/UMTS) network. Then, the eNodeB hands over the UE to a 2^(nd)generation/3^(rd) generation (2G/3G) network, that is, the UE chooses a2G/3G cell to camp. When the UE returns a page response to the MSC inthe GPRS/UMTS network, the UE completes processing of the MT service.

During research and practice of the prior art, however, the inventorfinds that the prior art has at least the following weaknesses:

By using the CS fallback method in the prior art, the eNodeB executes aPS service handover immediately when receiving the page message from theMME, which results in the following problems:

1. Waste of network resources. According to the prior art, when an MTservice arrives, the eNodeB hands over the PS service to the PS domainof a 2G/3G network and connects the MT service. In practice, thefollowing case often happens: When the UE is handed over to a 2G/3Gnetwork and an MT service is connected, the user rejects the MT servicebecause the user is unwilling or unable to answer. The base stationsubsystem/radio network controller (BSC/RNC) regards such MT services asservices that have been completed and the BSC/RNC then hands over the PSservices of the UE to the EPS network. Two PS service handovers areperformed for an MT service that is not normally executed, and thereforenetwork resources are wasted.

2. Impact on the ongoing PS service of the UE. For example, a UE is in aPS service (such as a video conference) in an EPS network when itreceives a CS MT service (such as a private call). According to theprior art, the eNodeB hands over the video conference to the PS domain a2G/3G network, but because the PS domain of the 2G/3G network does notsupport certain PS services in the EPS network, such as the videoconference, the PS service will fail. Thus, the prior art impacts theongoing PS services.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a method, system and devicefor processing CS services in an evolved packet network so as to avoidthe waste of network resources and not to impact the current PS servicesof a UE.

For the above purpose, the embodiments of the present invention areimplemented via the following technical solution:

A method for processing CS services in an evolved packet networkincludes:

-   -   receiving, by an MME, an MT service indication from an MSC;    -   sending, by the MME, the MT service indication to a UE; and    -   by the MME, receiving an MT service response returned by the UE        and performing subsequent operations according to the MT service        response.

A method for processing CS services in an evolved packet networkincludes:

-   -   receiving, by an MME, a short message from an MSC;    -   by the MME, sending the short message to a UE if the UE is in        active mode and activating the UE and sending the short message        to the UE if the UE is in idle mode; and    -   receiving, by the MME, a short message response from the UE.

An MME includes:

-   -   a page message receiving unit, configured to receive an MT        service indication from an MSC;    -   an MT service notifying unit, configured to send the MT service        indication to a UE;    -   a response receiving unit, configured to receive an MT service        response returned by the UE; and    -   a response processing unit, configured to perform subsequent        operations according to the MT service response.

An MME includes:

-   -   a receiving unit, configured to receive a short message from an        MSC;    -   a state judging unit, configured to judge whether a UE is in        active or idle mode;    -   a sending unit, configured to send the short message received by        the receiving unit to the UE when the state judging unit        determines that the UE is in active mode;    -   an activating and sending unit, configured to activate the UE        when the state judging unit determines that the UE is in idle        mode and send the short message received by the receiving unit        to the activated UE; and    -   a short message response receiving unit, configured to receive a        short message response from the UE.

A UE includes:

-   -   a notification receiving unit, configured to receive an MT        service indication sent by an MME;    -   an notifying unit, configured to notify the user of the MT        service after the notification receiving unit receives the MT        service indication; and    -   a response sending unit, configured to return an MT service        response to the MME according to a choice of the user regarding        the MT service.

A system for processing CS services in an evolved packet networkincludes an MSC and an MME, where:

-   -   the MSC includes a service indication sending unit, configured        to send an MT service indication to the MME after receiving the        MT service indication;    -   the MME includes:    -   a page message receiving unit, configured to receive the MT        service indication from the MSC;    -   an MT service notifying unit, configured to send the MT service        indication to a UE;    -   a response receiving unit, configured to receive an MT service        response returned by the UE; and    -   a response processing unit, configured to perform subsequent        operations according to the MT service response.

The technical solution provides the following benefits:

In the embodiments of the present invention, when a CS MT servicearrives, the MME sends an MT service indication to notify the UE of theMT service and then performs subsequent operations according to an MTservice response received from the UE. When the MT service arrives, theMME does not trigger the eNodeB to hand over the PS service of the UE,but notifies the UE of the MT service and carries out subsequentprocessing according to the MT service response returned by the UE.Thus, the embodiments of the present invention avoid the waste ofnetwork resources caused by a meaningless PS service handover and do notimpact the ongoing PS services of the UE.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of a CS fallback method provided in an embodimentof the present invention;

FIG. 2 is a signaling flow of a CS fallback method provided inEmbodiment 1 of the present invention;

FIG. 3 is a signaling flow where a UE is activated and notified of anincoming MT service in Embodiment 1 of the present invention;

FIG. 4 is a signaling flow of a CS fallback method provided inEmbodiment 2 of the present invention;

FIG. 5 is a signaling flow where a UE is activated and notified of anincoming MT service in Embodiment 2 of the present invention;

FIG. 6 is a signaling flow of an MT service restoring method provided inan embodiment of the present invention; and

FIG. 7 shows a structure of a CS fallback system provided in anembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

To better explain the purpose, technical solution and advantages of thepresent invention, the embodiments of the present invention arehereinafter described in detail with reference to the accompanyingdrawings.

When a circuit switched (CS) mobile terminated (MT) service arrives, asshown in FIG. 1, a CS fallback method provided in an embodiment of thepresent invention includes:

Step 101: A mobility management entity (MME) receives an MT serviceindication from an mobile switching center (MSC).

Step 102: The MME forwards the MT service indication to a user'sequipment (UE).

The MT service indication notifies the UE of an MT service.

Step 103: The MME receives an MT service response from the UE.

Step 104: The MME carries out subsequent processing according to the MTservice response.

The above is a CS fallback method provided in an embodiment of thepresent invention. In the embodiment, when a CS MT service arrives, theMME first sends an MT service indication to notify the UE of the MTservice and after reception of the MT service response from the UE, theMME carries out subsequent processing according to the MT serviceresponse. In the method provided in the embodiment of the presentinvention, when an MT service arrives, the MME does not trigger theeNodeB to hand over the PS service of the UE, but notifies the UE of theMT service and carries out subsequent processing according to the MTservice response returned by the UE. Thus, the method avoids the wasteof network resources caused by a meaningless PS service handover anddoes not impact the ongoing PS service of the UE.

In a specific implementation of the embodiment of the present invention,the MT service response may carry a user choice result. If the usechooses to reject the MT service, the MME returns an MT service Rejectmessage to the MSC when the MME carries out subsequent processingaccording to the MT service response.

If the user chooses to accept the MT service, the MME sends a PS servicehandover request to the eNodeB and the eNodeB executes a PS servicehandover when the eNodeB receives the handover request and hands the UEover to a 2G/3G network. After the UE is handed over to the 2G/3Gnetwork, the UE sends a first page response to the MSC and completes MTservice processing.

In another embodiment of the present invention, if the user chooses toaccept the MT service, the MME does not hand over the current PS serviceof the UE according to a configured network operation policy andtherefore, the MME does not need to send a PS service handover requestto the eNodeB and the eNodeB does not need to execute a PS handoverlater. In this case, after the UE sends the response indicatingacceptance of the MT service, or receives a response from the MMEregarding the UE's acceptance of the MT service, the UE accesses the2G/3G network directly to complete the MT service processing.

The above describes the CS fallback method provided in an embodiment ofthe present invention. The following describes specific signaling flowsof the method.

As shown in FIG. 2, a signaling flow of the CS fallback method inEmbodiment 1 of the present invention includes:

Step 201: The MSC receives an MT service indication and sends a firstpage message to the MME.

In practice, the first page message may carry an international mobilesubscriber identity (IMSI) of the UE.

Step 202: When receiving the first page message, the MME queries the UEstate. If the UE is in idle mode, the MME sends a second page message tothe eNodeB. If the UE is in active mode, the process proceeds to step205.

In practice, the first page message may carry the MT service indicationsent by the MSC to the MME. Therefore, the first page message may benamed MT service request or alike. In addition, if the first pagemessage carries the MT service indication, in step 302, after the MMEreceives the first page message, the MME needs to parse the first pagemessage and query the UE state after the MT service indication isobtained.

In addition, the first page message may not carry the MT serviceindication. In this case, the MME is set to query the UE state once itreceives the first page message. In this case, the first page message isequivalent to an MT service indication.

Step 203: The eNodeB broadcasts the second page message in the cell itmanages.

Step 204: The UE receives the second page message and returns a servicerequest to the MME.

The MME sends the second page message via the eNodeB to activate theidle UE.

Step 205: After receiving of the service request, the MME sends an MTservice indication to the UE. The MT service indication is intended tonotify the UE of the MT service.

The MT service indication shown in FIG. 2 is a non access stratum (NAS)message and therefore it may be sent to the UE directly from the MME. Inanother embodiment of the present invention, the MT service indicationis an access stratum message (such as Page). The access stratum messagemay carry the MT service indication and is sent by the MME to the eNodeBand forwarded by the eNodeB to the UE. This does not impact theimplementation of the present invention.

Step 206: After the UE receives the MT service indication, the UEnotifies the user of the MT service.

In practice, the UE notifies the user of the MT service according to thepresetting of the user. For example, the UE may ring, or vibrate, orring and vibrate, or give a text notify, to notify the user of the MTservice.

After the user makes a choice regarding the MT service, the UE executesstep 207.

Step 207: The UE sends an MT service response to the MME.

The MT service response may carry the user choice result (accept orreject) or the MT service response does not carry a user choice result,that is, the user choice result is null. If the MT service response doesnot carry a user choice result, the MME may decide the user choiceaccording to default settings. A common scenario is that, if the MTservice response does not carry the choice result, the MME thinks thatthe user accepts the MT service by default.

Step 208: The MME obtains the choice result carried in the MT serviceresponse. If the user chooses to reject the MT service, the MME sends afirst page reject message (the foregoing MT service reject). If the userchooses to accept the MT service, the process proceeds to step 209.

If the UE rejects the MT service, it is unnecessary to execute the MTservice and the MME returns a first page reject message to the MSC toend the MT service. In the method provided in the embodiment of thepresent invention, if the UE does not execute the MT service, the eNodeBdoes not hand over the PS service of the UE. Thus the method avoids thewaste of network resources caused by a meaningless PS handover and willnot impact the current PS service of the UE.

The first page reject message may carry a cause value indicating thereason for rejecting the MT service or the message may not carry thecause value. Whether the message carries the cause value does not impactthe implementation of the present invention.

In addition, the case often happens in daily life that the user does notsee or feel the notifying of the UE in a long time. To improve the workefficiency of the MME, it may be defined in advance that, if the MMEdoes not receive the MT service response from the UE within a presettime T, the MME thinks that the user rejects the MT service. And in thiscase, the MME sends the first page reject message to the MSC to rejectthe MT service.

Step 209: The MME sends a PS service handover request to the eNodeB.

Step 210: The eNodeB receives the PS service handover request andinitiates a PS service handover procedure to hand the UE over to the2G/3G network.

Step 211: After the UE is handed over to the 2G/3G network, the UE sendsa first page response and completes the MT service processing.

In another embodiment of the present invention, after the MME receivesthe first page message, the MME may not query the UE state but thinksthe UE is in idle mode by default. Then, the MME sends a second pagemessage and an MT service indication to the UE to notify the active oridle UE of the MT service.

The above is a signaling flow provided in Embodiment 1 of the presentinvention. When the MME receives the first page message sent by the MSCin step 201, the MME may notify an idle or active UE of the MT servicevia steps 202-205 in Embodiment 1 of the present invention or via thesignaling flow shown in FIG. 3. The signaling flow includes:

Step 301: The MME receives a first page message from the MSC and sends athird page message to the eNodeB. The third page message carries atleast an MT service indication.

In practice, the MT service indication may be a page cause value in thethird page message or an independent information element in the thirdpage message, which will not impact the implementation of the presentinvention.

Step 302: The eNodeB broadcasts the third page message in the cell itmanages.

Step 303: After the UE receives the third page message, the UE notifiesthe user of the MT service.

The signaling flow shown in FIG. 3 is different from steps 202-205 inEmbodiment 1 of the present invention in the following aspects:

In Embodiment 1 of the present invention, the MME sends a message tonotify the UE of an MT service only when the UE is in active mode. TheUE may be already in active mode when the MME receives the first pagemessage, or the UE may be activated through paging by the MME. In thesignaling flow shown in FIG. 3, however, the MME does not check whetherthe UE is in active mode but notifies the UE of an MT service directlyvia a third page message.

Specifically, in Embodiment 1 of the present invention, when the UE isin idle mode, the MME sends the second page message and the MT serviceindication to notify the UE of the MT service; when the UE is in activemode, the MME sends the MT service indication directly to notify the UEof the MT service. The benefit of this signaling flow is that it doesnot impact the paging mechanism in the existing EPS network.

In the signaling flow shown in FIG. 3, the MME sends a third pagemessage that carries the MT service indication to notify the UE of theMT service. The benefit is that it increases the processing efficiencyof the MME and reduces the call delay.

To let the UE know information of the MT service originator to help theuser make a choice regarding the MT service, in the preceding andfollowing embodiments of the present invention, the first page messagesent by the MSC to the MME may further carry MT service relatedinformation.

The MT service related information includes: a mobile station ISDN(MSISDN) of the originator, or a service type indication, such as shortmessage service (SMS), location service (LCS), and unstructuredsupplementary service data (USSD). In addition, to help the MSCdetermine the MT service associated with the received MT serviceresponse, the MT service related information may further include an MTservice ID that is allocated by the MSC or an existing ID (like a callnumber).

Because the first page message sent by the MSC to the MME carries the MTservice related information, the page message or MT service indicationsent by the MME to the UE may further carry the MT service relatedinformation. In this case, the UE notifies the user of the MT serviceaccording to the received MT service related information according tothe presetting of the user. For example, the UE may display the MSISDNof the originator to the user or notify the user of the service type.

In the foregoing method, the user may choose to accept or reject theservice. In certain scenarios, however, the user wishes to process theMT service after waiting for some time. It is therefore necessary tohold the MT service. Embodiment 2 of the present invention providesanother CS fallback method. The method includes the following step basedon the method shown in FIG. 1:

If the user chooses to hold the MT service, the MME sends an MT serviceHold message to the MSC.

In addition, to guarantee that the MT service is restorable, the methodfurther includes:

If the UE requests restoration of the held MT service, the MME notifiesthe MSC to restore the MT service; the MSC judges whether the MT servicecan be restored and if the service can be restored, the MSC notifies theUE of accessing the 2G/3G network via the MME and the UE then completesthe MT service, or the MME triggers the eNodeB to hand the UE over tothe 2G/3G network to complete the MT service according to a configuredoperation policy. If the MSC cannot restore the MT service, therestoration procedure is ended.

FIG. 4 shows a signaling flow of the CS fallback method in Embodiment 2of the present invention. The signaling flow allows the user to chooseto hold the MT service. The signaling flow includes:

Step 401: The MSC receives an MT service request and sends a first pagemessage to the MME.

To avoid long-term MT service holding that consumes system resources,the method may further include a step of presetting a call hold timerand the first page message further carries the call hold timer length.

Step 402: The MME queries the state of the UE associated with the IMSI.If the UE is in idle mode, the MME sends a fourth page message to theeNodeB. If the UE is in active mode, the process proceeds to step 405.

Step 403: The eNodeB broadcasts the fourth page message in the cell itmanages.

Step 404: The UE receives the fourth page message and returns a servicerequest to the MME.

Step 405: The MME sends an MT service indication to the UE to notify theUE of an MT service.

The ME service indication may or may not carry the MT service relatedinformation and/or the call hold timer length, which does not impact theimplementation of the present invention.

Step 406: After the UE receives the MT service indication, the UEnotifies the user of the MT service.

In practice, if the MT service indication carries the MT service relatedinformation, the UE notifies the user of the MT service according to thereceived MT service related information according to the presetting ofthe user. For example, the UE may display the MSISDN of the originatorto the user or notify the user of the service type. The UE may ring, orvibrate, or ring and vibrate, or give a text notify to notify the userof the MT service.

After the user makes a choice regarding the MT service, the UE executesstep 407.

Step 407: The UE sends an MT service response to the MME.

The MT service response may carry the user choice result (accept orreject) or the MT service response does not carry a user choice result,that is, the user choice result is null. If the MT service response doesnot carry a user choice result, the MME may decide the user choiceaccording to default settings. A common scenario is that, if the MTservice response does not carry the choice result, the MME thinks thatthe user accepts the MT service by default.

If the user chooses to hold the service, the UE starts the associatedtimer according to the call hold timer length.

Step 408: The MME obtains the choice result carried in the MT serviceresponse. If the user chooses to hold the MT service, the MME sends anMT service Hold message to the MSC; if the user chooses to reject oraccept the MT service, the subsequent steps are the same as theprocedure provided in Embodiment 1 of the present invention.

Step 409: The MSC starts the associated timer according to the presetcall hold timer length.

In another embodiment of the present invention, after the MME receivesthe first page message, the MME may not query the UE state but thinksthe UE is in idle mode by default. Then, the MME sends the fourth pagemessage and the MT service indication to the UE to notify the active oridle UE of the MT service.

The above is a specific signaling flow of the CS fallback methodprovided in Embodiment 2 of the present invention. The active or idle UEmay be notified of the MT service via steps 402-405. In anotherembodiment of the present invention, the signaling flow shown in FIG. 5may be adopted to notify an active or idle UE of an MT service. Thesignaling flow includes:

Step 501: The MME receives a first page message from the MSC and sends afifth page message to the eNodeB. The fifth page message carries atleast an MT service indication.

To avoid long-term MT service holding that consumes system resources andhelp the user make a choice regarding the MT service, the MT servicerequest may further carry a preset call hold timer length and/or MTservice related information.

Step 502: The eNodeB broadcasts the fifth page message in the cell itmanages.

Step 503: After the UE receives the fifth page message, the UE notifythe user of the MT service.

The CS fallback method provided in the embodiments of the presentinvention and the specific implementation procedures are describedabove.

For a user-held MT service, if the user chooses to continue the service,the MT service needs to be restored. When the user requests restorationof the MT service, if the UE starts a timer when the MT service is held,the UE needs to check whether the timer has expired. If the timer hasexpired, the restoration procedure is over. If the timer has notexpired, the restoration procedure is executed. With respect to theabove MT service restoration procedure, an embodiment of the presentinvention provides a signaling flow for MT service restoration. As shownin FIG. 6, the signaling flow includes:

Step 601: If the UE is currently in idle mode, the UE sends a servicerequest to the MME. When the UE becomes active from the idle mode, step602 is executed. If the UE is in active mode, step 602 is executeddirectly.

Step 602: The UE sends a first MT service activation request to the MME,requesting to restore the held MT service.

The MT service activation request may carry the ID of the MT service tobe activated so that the MME can determine the MT service. In certainscenarios (if the UE holds only one service), the MT service ID may notbe carried, which does not impact the implementation of the presentinvention.

Step 603: The MME sends a second MT service activation request to theMSC.

Step 604: After the MSC receives the second MT service activationrequest, the MSC matches the MT service ID with the held MT service. Ifthe service exists, the MSC accepts the activation request, stops thecall hold timer, allocates the requested resource, and sends a second MTservice activation response to the MME. The second MT service activationresponse carries a cause value of the successful operation. Otherwise,the MSC rejects the activation request and sends a second MT serviceactivation response to the MME. The second MT service activationresponse carries a cause value of the failed operation.

In addition, if the call hold timer in the MSC expires, the MSC stopsholding the MT service, releases the held resource, and stops the timer.

Optionally, different response messages may be sent to the MME in thescenarios of success and failure. The response message may also carrythe MT service ID to help the UE determine the MT service.

Step 605: When the MME receives the second MT service activationresponse, the MME may send a first MT service activation response to theUE.

The first MT service activation response may carry the MT service IDcarried in the second MT service activation response. Alternatively, theMME may not send the first MT service activation response and theimplementation of the present invention will not be impacted.

Step 606: The MME sends a PS service handover request to the eNodeB.

In practice, the MME may proceed without handing over the current PSservice of the UE according to the configured network operation policyand therefore the MME does not need to send a PS service handoverrequest to the eNodeB and the eNodeB does not need to execute the PShandover procedure.

Step 607: The eNodeB receives the PS service handover request andinitiates a PS service handover procedure to hand the UE over to the2G/3G network.

Step 608: After the UE is handed over to the 2G/3G network, the UE sendsthe first page response and completes the MT service processing.

The above describes the CS fallback method provided in the embodimentsof the present invention. In the CS fallback scenario, an SMS MT servicemay be sent to the UE via signaling of the UE in the EPS network withoutthe need to hand over the UE to a 2G/3G network. For example, the firstpage message may carry the short message content and then the shortmessage is sent to the UE via the EPS network. The UE receives the shortmessage and completes related processing.

Those skilled in the art may understand that all or part of the steps ofthe method in the above embodiments of the present invention may beimplemented by hardware under instructions of a program. The program maybe stored in a computer-readable storage medium. When the program isexecuted, the following steps are performed:

-   -   by an MME, receiving an MT service indication from an MSC;    -   sending the MT service indication to a UE; and    -   receiving an MT service response returned by the UE and        performing subsequent operations according to the MT service        response.

The storage medium may be a read-only memory, a magnetic disk or acompact disk.

FIG. 7 shows a CS fallback system provided in an embodiment of thepresent invention. The system includes: an MME 701, an MSC 702, and aneNodeB 703.

The MSC 702 includes a service indication sending unit 7021.

The service indication sending unit 7021 is configured to send an MTservice indication to the MME 701 after receiving the MT serviceindication.

The MME 701 provided in the embodiment of the present inventionincludes:

-   -   a page message receiving unit 7011, configured to receive the MT        service indication from the MSC 702;    -   an MT service notifying unit 7012, configured to send the MT        service indication to a UE 704;    -   a response receiving unit 7013, configured to receive the MT        service response returned by the UE 704; and    -   a response processing unit 7014, configured to perform        subsequent operations according to the MT service response.

In practice, the MT service response carries a user choice result andthe response processing unit 7014 includes:

-   -   a first response processing unit, configured to return an MT        service Reject message to the MSC 702 if the user chooses to        reject the MT service;    -   a second response processing unit, configured to return an MT        service Hold message to the MSC 702 if the user chooses to hold        the MT service; and    -   a third response processing unit, configured to trigger the UE        704 to access a 2G/3G network if the user chooses to accept the        MT service or if the user choice result is null.

To enable the UE to restore the held MT service, the MME 701 furtherincludes:

-   -   an activation request receiving unit, configured to receive a        first MT service activation request sent by the UE 704,        requesting to restore the held MT service;    -   an activation request sending unit, configured to send a second        MT service activation request to the MSC 702; and    -   an activation response receiving unit, configured to receive a        second MT service activation response returned by the MSC 702        and indicates to the UE 704 that the UE 704 should access the        2G/3G network.

The MSC 702 further includes:

-   -   an activation request receiving unit, configured to receive the        second MT service activation request from the MME; and    -   an activation response sending unit, configured to return the        second MT service activation response after the activation        request receiving unit receives the request.

Because some UEs are in idle mode in the EPS network, to activate theUEs, the MT service notifying unit 7012 includes:

-   -   a UE activating unit, configured to activate the UE 704 via the        eNodeB 703;    -   a state querying unit, configured to: query the state of the UE        704, and trigger a sending unit if the UE 704 is in active mode,        or trigger the UE activating unit if the UE 704 is in idle mode;        and    -   the sending unit, configured to send the MT service indication        to the UE 704 if the UE 704 is in active mode.

In practice, the UE activating unit has two implementations.

In the first implementation, the unit includes:

-   -   a page message sending unit, configured to send a second page        message to the eNodeB 703; and    -   a service request receiving unit, configured to trigger the MT        service notifying unit 7012 after receiving the service request        returned by the UE 704.

In the second implementation, the UE activating unit is an activatingand notifying unit.

The activating and notifying unit is configured to send a third pagemessage that carries an MT service indication to the eNodeB 703. Bysending the third page message to the eNodeB 703, the UE is activatedand the MT service indication is sent to the UE.

An embodiment of the present invention provides an MME for processing ofthe SMS MT service in a CS fallback scenario. The MME may include:

-   -   a receiving unit, configured to receive a short message from an        MSC;    -   a state judging unit, configured to judge whether a UE is in        active or idle mode;    -   a sending unit, configured to send the short message received by        the receiving unit to the UE when the state judging unit        determines that the UE is in active mode;    -   an activating and sending unit, configured to activate the UE        when the state judging unit determines that the UE is in idle        mode and send the short message received by the receiving unit        to the activated UE; and    -   a short message response receiving unit, configured to receive a        short message response from the UE.

The activating and sending unit may include:

-   -   a page sending unit, configured to send a second page message to        the eNodeB;    -   a returned message receiving unit, configured to receive a        service request returned by the UE; and    -   a short message sending unit, configured to send the short        message to the UE according to the service request received by        the returned message receiving unit.

Or, the activating and sending unit may include:

-   -   a page sending unit, configured to send a third page message        that carries the short message to the eNodeB.

FIG. 7 shows the UE 704 provided in an embodiment of the presentinvention. The UE 704 includes:

-   -   a notification receiving unit 7041, configured to receive the MT        service indication sent by the MME 701;    -   an notifying unit 7042, configured to notify the user of the MT        service after the notification receiving unit 7041 receives the        MT service indication; and    -   a response sending unit 7043, configured to return an MT service        response to the MME according to the choice of the user        regarding the MT service.

To make the held MT service restorable, the UE may further include:

-   -   an activation request sending unit, configured to send a first        MT service activation request to the MME, requesting to restore        the held MT service.

Further, the UE may include an MT service processing unit, configured toprocess the MT service.

Although the present invention has been described through severalexemplary embodiments, the invention is not limited to such embodiments.It is apparent that those skilled in the art can make variousmodifications and variations to the invention without departing from thespirit and scope of the present invention. The invention is intended tocover the modifications and variations provided that they fall withinthe scope of protection defined by the following claims or theirequivalents.

1. At a mobility management entity (MME) of a wireless network that usesa packet switched (PS) domain, a method for efficiently processingcircuit switched (CS) services in an evolved packet system (EPS), themethod comprising: receiving a mobile terminated (MT) service indicationfrom a mobile switching center (MSC); sending the MT service indicationto a user equipment (UE) to notify the UE of the MT service; receivingfrom the UE an MT service response, which includes a user choice result;and based on the user choice result in the MT service response,performing one or more subsequent operations according to the MT serviceresponse, which indicates a user choice to accept the MT service, rejectthe MT service, or a null response.
 2. The method of claim 1, whereinthe performing one or more subsequent operations comprises: determiningthat the user choice result is to reject the MT service; and returningan MT service reject message to the MSC.
 3. The method of claim 1,wherein the performing subsequent operations comprises: determining thatthe user choice result is to accept the MT service; and triggering theUE to access a 2^(nd) generation or 3^(rd) generation (2G/3G) network.4. The method of claim 3, wherein the triggering of the UE to access a2G/3G network comprises: sending a PS service handover request to anevolved NodeB (eNodeB), which then executes a PS service handover whenthe eNodeB receives the handover request by handing the UE over to a2G/3G network, which then sends a first page response to the MSC forcompleting the MT service processing.
 5. The method of claim 1, whereinthe performing one or more subsequent operations comprises: determiningthat the user choice result is to accept the MT service; and allowingthe the UE to access a 2G/3G network directly to complete the MT serviceprocessing without sending a response to the UE.
 6. The method of claim1, wherein the performing of one or more subsequent operationscomprises: determining that the user choice result is to accept the MTservice; and sending a PS service handover request to a eNodeB forallowing the UE to access a 2G/3G network directly to complete the MTservice processing.
 7. The method of claim 1, wherein the performing ofone or more subsequent operations comprises: determining that the userchoice result is a null; and setting the user choice result according toone or more default settings.
 8. The method of claim 1, wherein the MTservice indication comprises MT service related information, wherein theMT service related information comprises one of a mobile station ISDN(MSISDN) of an originator and a service type indication.
 9. The methodof claim 8, wherein the MT service related information further comprisesan MT service ID.
 10. The method of claim 1, further comprising:receiving, by the UE, the MT service indication, notifying the user ofthe MT service, and returning an MT service response to the MMEaccording to a choice of the user.
 11. The method of claim 1, furthercomprising: receiving, from the MSC, a first page message, wherein thefirst page message comprises an international mobile subscriber identity(IMSI) of the UE.
 12. The method of claim 11, wherein the first pagemessage comprises the MT service indication sent by the MSC to the MME.13. The method of claim 1, wherein the sending the MT service indicationto the UE comprises: querying a state of the UE; determining that the UEis in an active state; and based on the active state of the UE, sendingthe MT service indication to the UE.
 14. The method of claim 1, whereinthe sending the MT service indication to the UE comprises: querying astate of the UE; determining that the UE is in an idle mode state;activating the UE via an eNodeB; and sending the MT service indicationto the UE.
 15. The method of claim 14, wherein the activating the UE viathe eNodeB and sending the MT service indication to the UE comprises:sending a second page message to the eNodeB, which subsequentlybroadcasts the second page message to UEs in a cell managed by theeNodeB; receiving a service request returned by the UE; and sending theMT service indication to the UE.
 16. In a wireless network that uses apacket switched (PS) domain, a mobility management entity (MME) forefficiently processing circuit switched (CS) services in an evolvedpacket system (EPS), the MME comprising: a page message receiving unit,configured to receive a mobile terminated (MT) service indication from amobile switching center (MSC); an MT service notifying unit, configuredto send the MT service indication to a user equipment (UE) to notify theUE of the MT service; a response receiving unit, configured to receivean MT service response returned by the UE; and a response processingunit, configured to perform subsequent operations according to the MTservice response, wherein the MT service response comprises a userchoice result.
 17. The MME of claim 16, wherein the response processingunit comprises one of: a first response processing unit, configured toreturn an MT service Reject message to the MSC if the user choice resultis to reject the MT service; and a third response processing unit,configured to trigger the UE to access a 2^(nd) generation or 3^(rd)generation (2G/3G) network if the user choice result is to accept the MTservice.
 18. The MME of any of claims 16, wherein the MT servicenotifying unit comprises: a state querying unit, configured to: query astate of the UE and trigger a sending unit if the UE is in active mode;and the sending unit, configured to send the MT service indication tothe UE if the UE is in active mode.
 19. The MME of claim 18, wherein theMT service notifying unit further comprises: a page message sendingunit, configured to send a second page message to the eNodeB; and aservice request receiving unit, configured to trigger the MT servicenotifying unit after receiving a service request returned by the UE. 20.In a wireless network that uses a packet switched (PS) domain, a userequipment (UE) for efficiently processing circuit switched (CS) servicesin an evolved packet system (EPS), which comprises: a notificationreceiving unit, configured to receive a mobile terminated (MT) serviceindication sent by a mobility management entity (MME); an notifyingunit, configured to notify the user of the MT service after thenotification receiving unit receives the MT service indication; and aresponse sending unit, configured to return an MT service response tothe MME according to a choice of the user regarding the MT service,wherein the MT service response comprises the user choice result. 21.The UE of claim 20, further comprising: an MT service processing unit,configured to process the MT service.
 22. The UE of claim 20, whereinthe MT service indication comprises MT service related information, andwherein the MT service related information comprises one of a mobilestation ISDN (MSISDN) of an originator and a service type indication.23. The UE of claim 23, wherein the MT service indication furthercomprises an MT service ID.
 24. In a wireless network that uses a packetswitched (PS) domain, a system for efficiently processing circuitswitched (CS) services in an evolved packet system (EPS, the systemcomprising: a mobile switching center (MSC); and a mobility managemententity (MME), wherein the MSC comprises a service indication sendingunit, configured to send a mobile terminated (MT) service indication tothe MME after receiving the MT service indication, and wherein the MMEcomprises: a page message receiving unit, configured to receive the MTservice indication from the MSC; an MT service notifying unit,configured to send the MT service indication to a user equipment (UE) tonotify the UE of the MT service; a response receiving unit, configuredto receive an MT service response returned by the UE; and a responseprocessing unit, configured to perform subsequent operations accordingto the MT service response, wherein the MT service response comprises auser choice result.
 25. The system of claim 24, wherein the responseprocessing unit comprises one of: a first response processing unit,configured to return an MT service Reject message to the MSC if the userchoice result is to reject the MT service; or a third responseprocessing unit, configured to trigger the UE to access a 2^(nd)generation or 3^(rd) generation (2G/3G) network if the user choiceresult is to accept the MT service.
 26. The system of claim 24, whereinthe MSC further comprises: an activation request receiving unit,configured to receive the second MT service activation request from theMME; and an activation response sending unit, configured to return thesecond MT service activation response after the activation requestreceiving unit receives the request.
 27. The system of claim 24, furthercomprising an evolved NodeB (eNodeB) and the MME further comprises: a UEactivating unit, configured to activate the UE via the eNodeB; and astate querying unit, configured to: query a state of the UE and triggerthe MT service notifying unit if the UE is in active mode.
 28. Thesystem of claim 27, wherein the UE activating unit comprises: a pagemessage sending unit, configured to send a second page message to theeNodeB; and a service request receiving unit, configured to trigger theMT service notifying unit after receiving a service request returned bythe UE.